The use of aerosol generating devices for the treatment of a variety of respiratory diseases is an area of large interest. Inhalation provides for the delivery of aerosolized drugs to treat asthma, COPD and site-specific conditions, with reduced systemic adverse effects. A major challenge is providing a device that delivers an accurate, consistent, and verifiable dose, with a droplet size that is suitable for successful delivery of medication to the targeted lung passageways.
Dose verification, delivery and inhalation of the correct dose at prescribed times is important. Getting patients to use inhalers correctly is also a major problem. A need exists to insure that patients correctly use inhalers and that they administer the proper dose at prescribed times. Problems emerge when patients misuse or incorrectly administer a dose of their medication. Unexpected consequences occur when the patient stops taking medications, owing to not feeling any benefit, or when not seeing expected benefits or overuse the medication and increase the risk of over dosage. Physicians also face the problem of how to interpret and diagnose the prescribed treatment when the therapeutic result is not obtained.
Currently most inhaler systems such as metered dose inhalers (MDI) and pressurized metered dose inhalers (p-MDI) or pneumatic and ultrasonic-driven devices generally produce drops with high velocities and a wide range of droplet sizes including large droplet that have high momentum and kinetic energy. Droplets and aerosols with such high momentum do not reach the distal lung or lower pulmonary passageways but are deposited in the mouth and throat. As a result, larger total drug doses are required to achieve the desired deposition in targeted areas. These large doses increase the probability of unwanted side effects.
Aerosol plumes generated from current aerosol delivery systems, as a result of their high ejection velocities and the rapid expansion of the drug carrying propellant, may lead to localized cooling and subsequent condensation, deposition and crystallization of drug onto the ejector surfaces. Blockage of ejector apertures by deposited drug residue is also problematic.
This phenomenon of surface condensation is also a challenge for existing vibrating mesh or aperture plate nebulizers that are available on the market. In these systems, in order to prevent a buildup of drug onto mesh aperture surfaces, manufacturers require repeated washing and cleaning, as well as disinfection after a single use in order to prevent possible microbiological contamination. Other challenges include delivery of viscous drugs and suspensions that can clog the apertures or pores and lead to inefficiency or inaccurate drug delivery to patients or render the device inoperable. Also, the use of detergents or other cleaning or sterilizing fluids may damage the ejector mechanism or other parts of the nebulizer and lead to uncertainty as to the ability of the device to deliver a correct dose to the patient or state of performance of the device.
Accordingly, there is a need for an inhaler device that delivers particles of a suitable size range, avoids surface fluid deposition and blockage of apertures, with a dose that is verifiable, and provides feedback regarding correct and consistent usage of the inhaler to patient and professional such as physician, pharmacist or therapist.